The background of the present invention is found mostly in the art of vehicles travelling in a water medium, which I will briefly review, since some of the thinking and concepts carry over to the present invention which deals with the construction of hydrofoil type of vehicle for travelling in a snow medium.
A hydrofoil vehicle is characterized by foils which contact the medium (be it water or snow) and support the main body of the vehicle through strut means, above the medium. Both the foils and the struts have a limited frontal area and the foils are additionally characterized by having a substantial under surface area for supporting the vehicle against the medium. Thus, the drag developed between the vehicle and the medium is minimized.
This theory was well established back in 1898 when the first hydrofoil boat was built and tested. In 1918 the eminent Alexander Graham Bell built and tested a hydrofoil boat, and achieved a record speed of 70 m.p.h.
Further reference on a hydrofoil system per se can be found in a Report on Hydrofoil Development submitted on June 27, 1960 to the U.S. House of Representatives, 86th Congress--2nd Session by its Committee on Science and Astronautics, and printed by the Govt. Printing Office, which is herein incorporated by reference.
To put the present invention in perspective it may be proper to analyze some unique aspects of the ski-bob (throughout the test of this application the term "ski-bob" will mean a power driven ski-bob, and the term snowfoil ski-bob will means a ski-bob incorporating the present invention).
Designing a ski-bob bares some similarities to designing an airplane, that is, it is important to optimize the various design parameters since over-designing cannot be tolerated. For example, if the drag characteristics (the resistance developed by the snow on the propagation of the ski-bob) are not minimized, a larger tread and engine will be called for, requiring in-turn a heavier, bulkier frame which in turn further increases the drag. Eventually, this mutual degeneration of design parameters leads to having a bulky vehicle like a snowmobile which weighs approximately 500 pounds and commonly uses a 40 horsepower engine in contrast to a ski-bob which weighs only about 35 pounds and which can be propelled by a 31/2 horsepower engine.
Thus, an affect of the present invention is to teach an important improvement for minimizing the drag imposed by soft snow on a ski-bob.